Cook Islands Prime Minister Henry Puna will stand down in September after nearly a decade.
Mr Puna plans to put his name forward to become the Secretary General of the Pacific Islands Forum at the end of the year.
The Cook Islands Party leader will stand aside so he can commit to competing for the role at the regional body, which is elected by the region's governments.
His deputy and Finance Minister Mark Brown will take over as prime minister.
In a statement, Mr Puna said the move came after lengthy consideration and many months of talks.
The MP for Manihiki said he was proud of the direction the Cook Islands had taken in the past decade, pointing to the country's economic development, tourism boom, renewable energy development and the creation of the Marae Moana marine reserve.
But he said the coronavirus pandemic was an "unfortunate interruption" to the process, stressing the importance of a smooth transition.